Microprocessors in computers are typically mounted on a motherboard either by direct attachment to the motherboard or by reception in a socket which is mounted on the motherboard. An evolving trend which is directed to enhancing computer capabilities is to mount the microprocessor on a separate processor board along with memory devices, and then mate the processor board to the mother board. Size considerations for laptop computers require that the processor board be mounted in a closely spaced-apart, parallel relationship with the mother board. Electrical connectors are known for interconnecting circuit boards in parallel, spaced-apart relationship. A problem with these connectors is that they have a relatively low number of input/output (I/O) terminals arranged in a dual row linear array. In order to accommodate the enhanced microprocessors having hundreds of I/O's, the known connectors would need to be excessively long. Therefore, it would be desirable to arrange the I/O's in a grid of multiple columns and rows. Currently there is no suitable connector which permits circuit board interconnections through a grid array. Further, due to the continuing trend toward miniaturization of computers and other electronic devices, connectors for electrically mating circuit boards are constantly being reduced in size. As the connectors become smaller, it becomes increasingly difficult to align the mating halves of an electrical connector assembly. There is a need for a connector assembly which provides alignment and mating features in a small size package.